Soy Isoflavones and Breast Cancer Risk Reduction

Phase 2

Completed

• Conditions: Breast Cancer
• Interventions: Dietary Supplement: isoflavones; Dietary Supplement: carbohydrate

• Registration Number: NCT00204490
• Lead Sponsor: The University of Texas Medical Branch, Galveston

Brief Summary

Soy consumption has been associated with reduced risk for developing breast cancer. Soy contains isoflavones which are weak estrogens. The roles of soy isoflavones in reducing breast cancer risk are currently unclear. Breast density has been considered as a breast cancer risk marker. We hypothesize that because isoflavones have estrogen-like activities, breast density and possibly bone density will be lower in women on soy-isoflavones.

Detailed Description

This is a randomized, double-blind study, with two arms and 100 women in each arm. Premenopausal women will be recruited and randomly allocated to take one of the two different dietary supplements in pills daily for 2 years. The two supplements are soy isoflavones (treatment) and placebo (carbohydrates). Both treatment and placebo pills will contain multi-vitamins and minerals. Multiple blood, urine, and breast fluid samples will be obtained before and during the dietary supplement periods and analyzed for biomarkers of breast cancer risk. At baseline and after the intervention period, breast density and bone density will be assessed by radiologic techniques. The efficacy of the dietary intervention will be determined by comparing mean changes of serum markers for breast cancer risk,dense breast tissue, and bone mineral density over the two year dietary intervention period in the two supplement groups with adjustment for baseline values and individual patient characteristics of interest. We predict that 2 years of soy isoflavone supplement will reduce breast density, which may be explained by individual changes in serum markers of breast cancer risk.

Study Timeline

• Study Start: 2004-04
• Study First Submitted: 2005-09-12
• Study First Submitted QC: 2005-09-12
• Study First Posted: 2005-09-20
• Primary Completion: 2012-12-10
• Study Completion: 2023-05-31
• Results First Submitted: 2023-12-05
• Status Verified: 2024-05
• Results First Submitted QC: 2024-05-08
• Last Update Submitted: 2024-05-08
• Results First Posted: 2024-05-16
• Last Update Posted: 2024-05-16

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Female
• Target Recruitment: 197

Inclusion Criteria

• healthy premenopausal women
• 30 to 42 years old
• normal mammograms
• regular menstrual cycles

Exclusion Criteria

• abnormal mammograms
• first degree relatives with breast cancer
• pregnant or lactating
• peri- or post-menopause
• breast augmentation, reduction or lifting
• on oral contraceptive medications or exogenous hormones
• medically prescribed diets
• allergic reaction to soy products

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
1	isoflavones	soy isoflavones
2	carbohydrate	carbohydrates (maltodextrin)

Primary Outcome Measures

Name	Time	Method
Fibroglandular Tissue in Total Breast (FGBT%)	baseline, and after year 1 and 2 of supplementation	Effects of 1 and 2 years of treatment with isoflavones on percent of changes in FGBT%.
Breast Density by Mammography	baseline, and after year 1 and 2 of supplementation	Area of FGBT in mammogram. The timepoints were combined and summed.

Secondary Outcome Measures

Name	Time	Method
Bone Mineral Density	one and two years after dietary supplement	Bone mineral density of hip, spine and whole body bone mineral density as measured by dual x-ray absorptiometry. The timepoints were combined and summed.

Trial Locations

Locations (1)

General Clinical Reserach Center, The University of Texas Medical Branch; 🇺🇸 Galveston, Texas, United States